Velvet worms

What is a velvet worm? Velvet worms are terrestrial, soft-bodied, many-legged carnivores. They form the phylum Onychophora (‘claw bearers’ — each of their many limbs terminates in paired claws). Velvet worms range in size from around 10 millimetres long to relative giants in excess of 20 centimetres, and known species have between 13 and 43 pairs of stubby limbs termed lobopods. Unlike arthropods, velvet worms do not have an exoskeleton, hence their limbs have no need for joints to facilitate mobility. On the head is a pair of sensory antennae, and small eyes. The mouth has a characteristic set of sclerotised jaws, and is flanked by two prominent papillae — the source of the animals’ unique mode of prey capture discussed below. The skin is velvety because of the presence of dermal papillae covered with hydrophobic scales. Velvet worms come in many colours among and even within species, possibly a camouflage function (Figure 1). They have a certain mystique given their ‘ancient’ appearance and various curiosities, and a popular appeal — velvet worms are among few invertebrates for which dedicated conservation reserves have been created (in Australia, New Zealand and Brazil).